This invention relates to a burner for the combustion of oxidizable substances in a carrier gas, and a process for burning combustibles. In a preferred embodiment, the present invention relates to a burner for a thermal post-combustion device, typically used in the printing industry, to burn effluent containing environmentally hazardous constituents, and a process for burning combustibles with such a burner.
Recently, environmental considerations have dictated that effluent released to atmosphere contain very low levels of hazardous substances; national and international NOx emission regulations are becoming more stringent.
NOx emissions are typically formed in the following manner. Fuel-related NOx are formed by the release of chemically bound nitrogen in fuels during the process of combustion. Thermal NOx is formed by maintaining a process stream containing molecular oxygen and nitrogen at elevated temperatures in or after the flame. The longer the period of contact or the higher the temperature, the greater the NOx formation. Most NOx formed by a process is thermal NOx. Prompt NOx is formed by atmospheric oxygen and nitrogen in the main combustion zone where the process is rich in free radicals. This emission can be as high as 30% of total, depending upon the concentration of radicals present.
In order to ensure the viability of thermal oxidation as a volatile organic compound (VOC) control technique, lower NOx emissions burners must be developed.
It is therefore an object of the present invention to provide a raw gas burner which minimizes NOx formation by controlling the conditions that are conducive to NOx formation.